


Behind Closed Doors

by AstridRaine



Category: Shadowhunters (TV), The Mortal Instruments Series - Cassandra Clare
Genre: Alec is head of the Institute, Alternate Universe - Canon Divergence, Amused!Simon, Been a while since I last wrote something, Confused but Helpful!Simon, Cuddles, Cuddly!Jace, Cute, First Shadowhunters one-shot, Fluff, I swear, Jace has mood swings, Jace is obviously a Shadowhunter, M/M, Maybe some angst, Mood Swings, Moody!Jace, One-Shot, Simon is still a daylighter, Sleepy Cuddles, drunk!jace, jimon, just to make way for the fluff, moody
Language: English
Status: Completed
Published: 2019-04-13
Updated: 2019-04-13
Packaged: 2019-11-27 03:12:41
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings, No Archive Warnings Apply
Chapters: 1
Words: 1,603
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18189032
Author URL: https://archiveofourown.org/users/AstridRaine/pseuds/AstridRaine
Summary: His friends had warned him of this when he started dating Jace, but they never told him how adorably entertaining Jace was.





	Behind Closed Doors

Clary _had_ warned him of this. Izzy had too. Heck, even Alec had pulled him aside to tell him all about his parabatai and his...phases.

Simon was confused at first, of course, he would be. Each and every one of his friends were warning him that Jace's mood swings were not like any other. Clary had even compared them to women's period mood swings. Simon knew it must be bad if his best friend dared to compare something to period mood swings. 

But, as time went on, Simon stopped watching over his blond boyfriend, waiting for one of these "mood swings" to occur and came to the conclusion that they must have gone away after Jace started dating Simon. Simon didn't deny that his smile was a little brighter after that thought crossed his mind. 

But then the day came, and Simon was never more surprised. 

They had bought a little flat for themselves, the idea came to mind when they saw Alec practically living at Magnus's place. Clary and Izzy still stayed at the Institute, but they weren't dating, at least that's what Simon thought. At first, Jace had insisted on staying in the guest bedroom instead of both of them sharing a bed. Simon understood that he knew Jace wasn't that fond of expressing emotions and understanding what he was feeling. This little decision lasted for about a month before Simon woke up to Jace crawling into his bed and curling up at the very edge. 

Simon wanted none of that and pulled the shaking blond right into his arms with a teasing _"you want to turn into an icicle, Jace? I thought you loved being hot?"_   Jace had grumbled and half-heartedly swatted at Simon without opening his eyes. Although, Simon was pleased to notice that his boyfriend snuggled closer to Simon instead of pulling away like he used to. 

They barely used the guest bedroom now. 

It took about three months for Jace to finally warm up to Simon in a way that kisses and spontaneous hugs from the Daylighter. His nightmares had dwindled to about barely any since he had started sleeping with Simon. Of course, Jace was still his normal grumpy self around Simon because that's just how they worked but behind the closed doors, the pair of them were something completely different, and Simon was okay with that. At least he managed to nab the hot blond shadowhunter than everyone gossiped about. 

Simon was busy 24/7 due to some Downworlder and Nephilim truce that Alec had forged with Maia and a grudging Raphael. Nowadays, shadowhunter and downworlder missions had increased, especially after Valentine's and Sebastian's downfall. He and Jace barely had time to spend together and Simon couldn't wait until Friday was over so that he could take his much-needed break, according to Raphael, he was working much too hard and the elder vampire had forced him to rest up because he looked dead on his feet, pun fully intended. Raphael had pointedly ignored Simon's protests and stated firmly that they were not short on vampires and the last thing he, as the leader, needed was their youngest one passing out. 

Simon knew the "heartless" vampire did, in fact, care about him. Just like with Jace, he just had to probe and push at the barriers. 

Friday had come at last and Simon was excited as ever loving hell to get Jace and drag him back to their flat and put on Star Wars, even though he had watched the damn thing countless times, and cuddle up to his blond boyfriend. 

"Hey, Alec!" Simon called from his side in the Institue as he fumbled for his jacket and tried to zip it up and look for the black haired shadowhunter at the same time, "where's Jace?"

"Not here," Alec called back from where he was conversing in low voices with Izzy, and Magnus. "Although you might want to check your flat, the parabatai bond's been acting up all day." 

To any other person, Alec's voice could be considered as casual or blank, but to Simon who knew him for quite some time, he could clearly see, from his spot on the other side of the Institute, the unconcealed worry in Alec's bright blue orbs and the laced concern the Institute Head bore for his parabatai. 

 "Alright," Simon said his tone still cheerful. He knew how oppressive being the Head of the Institute was (well Simon usually compared it to Raphael being the leader of the Vampire coven, and based on Raphael's continuous complaints and grumbles, Simon had a feeling that being the leader wasn't always the best). "I'm heading out, tell Clary I said hi!" Simon waved at both Izzy and Alec and gave Magnus a two-fingered salute before heading out the doors. 

"Tell me if anything's wrong, okay?" He heard Alec's voice distantly from behind and waved a hand back to show he had heard. Internally, he hoped that Jace hadn't thrown himself into anything stupid, especially when he felt like he was useless. It was a common feeling for Jace, especially after the whole Valentine spiel. He worried about being good enough for the other Shadowhunters for so long and so hard that it took ages for Simon and the rest of their friends to tell him otherwise. 

Thanks to his vampire speed, it took Simon less time to reach their apartment than if he were a mundane. Opening the door, Simon braced himself for...anything, Jace being weird, spazzy demons attacking. Hell even a rogue Downworlder (some of them weren't happy with the truce) or likewise an angry Nephilim (same reason). 

But the scene in front of Simon made his heart melt if it was still beating. Jace was all curled up on their couch with the remote held aloft in his hand, the glow of the television screen flickering in front of him. His blond hair was all mussed and untidy, and if Simon looked close enough, he could see the black shadows under his eyes. All in all, this was not how Jace looked like ever, and Simon had a sinking feeling as to what's wrong, even when Jace looked so adorable. 

"Jace?" The blond jerked up from his blanket burrito and looked around blearily. Finally, his eyes came to a rest on Simon and instead of the normal half-smirk that the Daylighter also got greeted with, Jace turned away from him without a word and burrowed himself farther into the blankets. 

Now Simon was getting pretty worried. He marched over to where his boyfriend sat and plopped down close to the blond since Jace was in between Simon and the end of the couch, he has no room to move away from. 

Jace grumbled something unintelligible as soon as he came to that same exact realization and pushed Simon away harshly, "move for Angel's sake, Lewis!"

"Why Jace!" Simon gasped, pretending to look wounded and clutching his chest, "I can't even spend time with my gorgeous boyfriend?" 

Jace stopped grumbling and peeked up at Simon through long lashes, Simon pretended to not notice the red rimming his partners eyes, he knew how closed off Jace would get if Simon coddled him. 

"Fine," the blond said at last before standing up clumsily and swaying a bit before stumbling over to Simon. Right when the blond practically collapsed into Simon's arms, the Daylighter noticed the empty wine bottle laying on the ground beside the couch. _Dammit, Jace._  Simon thought fondly as he effortlessly scooped up his boyfriend bridal style and made his way to their bedroom. 

After gently depositing Jace, who may or may not have let out the most cutest yawn ever, Simon was about to go to their closet to change out of his grimy Shadowhunter uniform, that Alec and Clary had nearly forced him to wear. As he strode away from the bed, he felt himself suddenly tugged back onto the bed. He sprawled on top of Jace who let out a sleepy snuffle and curled tightly around him and closed his eyes. 

"Jace, I have to change," Simon tried to explain, "I'm all sweaty and gross, and I haven't had a shower and-"

"Don't care," Jace mumbled sleepily, wrapping his arms around Simon's midriff and pulling him closer until he was practically half on the blond and half on the bed, "want you with me now."

"Aw Jace," Simon cooed, carding a hand through the thick blond locks, "you never told me you were such a sap."

"Shut up!" Jace mumbled, swatting at Simon's face without opening his eyes, "I love you."

All fun and humor went instantly at those three words, Simon gaped at the now still and soundly sleeping form of his boyfriend. Did Jace really just say that? His Jace, the most emotionally constipated guy he's ever known? He felt love and pure happiness seep through his body as Jace snuggled closer and mumbled something unintelligible. He may be the hottest Shadowhunter, but there was also no doubt that he was indeed the cutest as well, and the proof was right in front of Simon. 

"I love you too, Jace," Simon softly kissed Jace's forehead and wrapped his arms around his shorter boyfriend. Tomorrow he would ask Jace why he wasn't at the Institute today, and maybe they would have a talk about his sudden mood swings (or is it phases?). But one thing's for sure, Simon loved Jace Herondale dearly and he had no intentions of letting him go, no matter what emotional baggage the other has, or what happens behind closed doors.  

**Author's Note:**

> This is my first Shadowhunters one-shot so I hope you guys liked it! I'm trying to incorporate ALL the fandoms I'm currently into my Ao3 account.  
> Hope you guys liked it <3
> 
> ~Astrid


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